ABSTRACT
Rules of this kind can be misused in circular arguments, which prove nothing. You should recognise our next one. I used it in Chapter 4, when I introduced the argument: 'Women who get raped ask for it.' 'What do you mean?' 'Well if they didn't they wouldn't get raped, would they?'. I pointed out that this has the logical form
If not Q then not P __________ If P then Q
and is VALID, but only because it is circular: a premise and conclusion of this form state exactly the same thing in different ways.